Veritas Storage Foundation for Oracle 5.0 Administrator's Guide, HP-UX 11i v3, Second Edition, December 2008

a high read ratio, however, RAID-5 performance is similar to that of a striped
volume.
Volume configuration guidelines
Follow these guidelines when selecting volume layouts:
■ Put the database log files on a file system created on a striped and mirrored
(RAID-0+1) volume separate from the index or data tablespaces. Stripe multiple
devices to create larger volumes if needed. Use mirroring to improve reliability.
Do not use VxVM RAID-5 for redo logs.
■ When normal system availability is acceptable, put the tablespaces on file
systems created on striped volumes for most OLTP workloads.
■ Create striped volumes across at least four disks. Try to stripe across disk
controllers. For sequential scans, do not stripe across too many disks or
controllers. The single thread that processes sequential scans may not be able
to keep up with the disk speed.
■ For most workloads, use the default 64 K stripe-unit size for striped volumes
and 16 K for RAID-5 volumes.
■ When system availability is critical, use mirroring for most write-intensive
OLTP workloads. Turn on Dirty Region Logging (DRL) to allow fast volume
resynchronization in the event of a system crash.
■ When system availability is critical, use RAID-5 for read-intensive OLTP
workloads to improve database performance and availability. Use RAID-5 logs
to allow fast volume resynchronization in the event of a system crash.
■ For most decision support system (DSS) workloads, where sequential scans
are common, experiment with different striping strategies and stripe-unit
sizes. Put the most frequently accessed tables or tables that are accessed
together on separate striped volumes to improve the bandwidth of data transfer.
See “About tuning VxVM ” on page 287.
Creating a volume
Veritas Volume Manager uses logical volumes to organize and manage disk space.
A volume is made up of portions of one or more physical disks, so it does not have
the limitations of a physical disk.
For databases where the data storage needs to be resilient and the data layout
needs to be optimized for maximum performance, we recommend using VxVM.
The striping and mirroring capabilities offered by a volume manager will help
you achieve your manageability, availability, and performance goals.
Setting up databases
Creating a volume
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